/* Name      : ???? 
 * Version   : 1.0
 * Date      : 2012-11-24
 * New       : Null
 * Func&Feat : 
 * State     : Design
 */
//char infection(int,int,char room[][]);
int main()
{
    int n,m,infector=0;
    char room[100][101];
    cin>>n;
    for(int i=0;i<n;i++)cin>>room[i];
    cin>>m;
    for(int d=1;d<m;d++)
    {
        for(int i=0;i<n;i++)
            for(int j=0;j<n;j++)
                if(room[i][j]=='@')
                {
                    if(i>0&&room[i-1][j]=='.')room[i-1][j]='$';
                    if(i<n-1&&room[i+1][j]=='.')room[i+1][j]='$';
                    if(j>0&&room[i][j-1]=='.')room[i][j-1]='$';
                    if(j<n-1&&room[i][j+1]=='.')room[i][j+1]='$';
                }
        for(int i=0;i<n;i++)
            for(int j=0;j<n;j++)
                if(room[i][j]=='$')room[i][j]='@';
/*        cout<<"?"<<d+2<<"??"<<endl;
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<n;j++)cout<<room[i][j];
            cout<<endl;
        }
        cout<<endl;//*/
    }
    for(int i=0;i<n;i++)
        for(int j=0;j<n;j++)
            if(room[i][j]=='@')infector++;
    cout<<infector;
    return 0;
}
